[ONNX] Fix import of boolean tensor constants (#4064)

Currently the shape and element type of boolean tensor attributes are
incorrect, since they use the shape/dtype of the packed numpy array
rather than of the original tensor value. Specifying the shape and
element type explicitly resolves this.

Author: rkayaith

python/torch_mlir/extras/onnx_importer.py

@@ -1137,7 +1137,8 @@ def get_operator_function(
             axis=None,
             bitorder="little",
         ),
-        signless=False,
+        shape=tp.dims,
+        type=IntegerType.get_signless(1),
     ),
     onnx.TensorProto.DataType.UINT8: lambda tp: DenseElementsAttr.get(
         np.asarray(tp.int32_data, dtype=np.uint8).reshape(tp.dims), signless=False

test/python/onnx_importer/constants.py

@@ -0,0 +1,32 @@
+# Licensed under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+# RUN: %PYTHON %s %t.onnx
+# RUN: %PYTHON -m torch_mlir.tools.import_onnx %t.onnx > %t.mlir
+# RUN: FileCheck %s < %t.mlir
+
+import onnx
+from onnx.helper import make_graph, make_tensor, make_tensor_value_info
+
+graph = make_graph(
+    name="graph",
+    inputs=[],
+    nodes=[],
+    outputs=[],
+    initializer=[
+        # CHECK{LITERAL}: torch.operator "onnx.Constant"() {torch.onnx.value = dense<[[true, false], [false, true]]> : tensor<2x2xi1>} : () -> !torch.vtensor<[2,2],i1>
+        make_tensor(
+            "bool_tensor",
+            onnx.TensorProto.BOOL,
+            dims=[2, 2],
+            vals=[True, False, False, True],
+        )
+    ],
+)
+model = onnx.helper.make_model(graph)
+
+import sys
+
+out_file_path = sys.argv[1]
+onnx.save(model, out_file_path)